Ignore:
Timestamp:
2024-09-20T12:16:28Z (6 months ago)
Author:
Jiří Zárevúcky <zarevucky.jiri@…>
Branches:
master
Children:
d3109ff
Parents:
2cf8f994
git-author:
Jiří Zárevúcky <zarevucky.jiri@…> (2024-09-20 11:42:13)
git-committer:
Jiří Zárevúcky <zarevucky.jiri@…> (2024-09-20 12:16:28)
Message:

Simplify the SYS_THREAD_CREATE syscall interface

Removed the beefy uarg structure. Instead, the syscall gets two
parameters: %pc (program counter) and %sp (stack pointer). It starts
a thread with those values in corresponding registers, with no other
fuss whatsoever.

libc initializes threads by storing any other needed arguments on
the stack and retrieving them in thread_entry. Importantly, this
includes the address of the
thread_main function which is now
called indirectly to fix dynamic linking issues on some archs.

There's a bit of weirdness on SPARC and IA-64, because of their
stacked register handling. The current solution is that we require
some space *above* the stack pointer to be available for those
architectures. I think for SPARC, it can be made more normal.

For the remaining ones, we can (probably) just set the initial
%sp to the top edge of the stack. There's some lingering offsets
on some archs just because I didn't want to accidentally break
anything. The initial thread bringup should be functionally
unchanged from the previous state, and no binaries are currently
multithreaded except thread1 test, so there should be minimal
risk of breakage. Naturally, I tested all available emulator
builds, save for msim.

File:
1 edited

Legend:

Unmodified
Added
Removed
  • uspace/lib/c/arch/mips32/src/thread_entry.S

    r2cf8f994 r3fcea34  
    4040#
    4141SYMBOL(__thread_entry)
    42         .ent __thread_entry
    43         .frame $sp, ABI_STACK_FRAME, $ra
    44         .cpload $t9
     42        # All registers should be zero, including $fp and $ra.
     43        # Instead of setting up a stack frame here, we leave it for __thread_main.
    4544
    46         #
    47         # v0 contains address of uarg.
    48         #
    49         add $a0, $v0, 0
     45        # Function argument.
     46        lw $a0, -4($sp)
     47        # Function pointer.
     48        lw $t0, -8($sp)
    5049
    51         # Allocate the stack frame.
    52         addiu $sp, -ABI_STACK_FRAME
    53 
    54         # Allow PIC code
    55         .cprestore 16
    56 
    57         jal __thread_main
     50        j $t0
    5851        nop
    59 
    60         #
    61         # Not reached.
    62         #
    63         addiu $sp, ABI_STACK_FRAME
    64         .end __thread_entry
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